The Peromyscus Genetic Stock Center is a unique facility. The Stock Center is unmatched for its role as a reliable source of disease free peromyscines, and unmatched for the variety of Peromyscus species and mutants available. The Stock Center is utilized by researchers in a wide range of fields, including human infectious disease. Peromyscines came to the Nation's attention in recent years for their role as the primary reservoir of two emerging infectious disease microorganisms. One of these, hantavirus, causes a disease with near 40% mortality, and is on the list of potential bioterrorism agents. The other one is the etiological agent of Lyme disease, a debilitating disease which counts 15,000 new cases annually. Stock Center resources are used extensively by investigators studying these and other diseases such as Ehrlichiosis, babesiosis and plague. Other research areas benefiting from Stock Center resources include the mechanism and cure of repetitive movement disorders, the genetics of disrupted genomic imprinting, the physiological basis of social behavior, and environmental toxicology. To continue supporting these research endeavors the Stock Center proposes: 1) to continue providing peromyscines for biomedical and related research, 2) to promote the species and its advantages, and 3) to improve the usefulness of Peromyscus as a laboratory model. Funds are requested to enable development of the sperm cryopreservation technology to provide a more economical means of storing some of the rare mutants maintained by the Stock Center. Funds are also requested to support the construction of a Peromyscus genomics database, and to use fluorescence in situ hybridization to globally determine regions of homology between Mus and Peromyscus, thereby expediting development of a linkage map.